"It is quite clear that there is now a massive $10 billion hole in the $30 billion they are claiming," Mr Rudd told reporters in Melbourne on Thursday.

"This is a $10 billion fraud on the Australian people."

Mr Abbott said his figures were produced by the PBO and validated by three distinguished public finance experts - Geoff Carmody, co-founder of Access Economics, Len Scanlan, former Queensland auditor-general and Professor Peter Shergold, former secretary of the department of Prime Minister and Cabinet.

"Let's be very clear, Mr Rudd has got all of his own figures wrong, now he is getting our figures wrong too," Mr Abbott told reporters in Sydney.

"When it comes to budget figures, when Mr Rudd's lips are moving you know he is not telling the truth."

Labor pointed to a document from April in which the PBO estimated more than 20,000 public service jobs would need to go to deliver the $5.2 billion claimed by the coalition.

Mr Hockey said this advice not only used quite different assumptions, it pre-dated the Pre-election Economic and Fiscal Outlook and his own costings from the PBO.

"It is plainly dishonest of the government to assert that its figures represent a costing of the coalition's position," he said in a statement.

Labor also raised questions over the coalition's assumptions over not proceeding with Labor's low income superannuation contribution, and savings measures linked to scrapping the carbon tax.

Mr Bowen said "history was repeating" itself after the coalition's 2010 costings were found to have an $11 billion black hole after the election.

The coalition has promised to release a full list of its election promises, both savings and expenditure, next week.

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